An ice making device has been known in which a series of operations from supplying water to an ice tray to storing ice pieces into a container are automatically performed. In the ice making device, a state within the ice tray (a state that water is existed, a state that ice pieces are existed, and a state that the ice tray is empty) is detected by various methods and an actuator and the like are controlled so as to perform a series of operations depending on a state within the ice tray. For example, in Japanese Patent Laid-Open No. 2005-315472 and Japanese Patent Laid-Open No. 2011-012916, ice making devices are disclosed in which a state within an ice tray is detected by reflection of light (optical sensor) or temperature (temperature sensor). Further, in US 2006/0201170, an ice making device is disclosed in which a water-supply quantity to an ice tray is accurately controlled by an electrostatic capacity sensor.
However, a structure which detects a state within an ice tray through reflection of light or by a temperature sensor is easily affected by states of water and ice existed within the ice tray and variation of ambient temperature and thus the state within the ice tray may not be detected accurately. Especially, in the structure which detects a state within an ice tray through reflection of light, the reflectivity of light is varied by the surface of water and ice in a wavy state and thus the state cannot be detected accurately. In an ice making compartment which is provided in a refrigerator, an ice tray may be shaken by vibration accompanied with opening and closing of its door (including another door in addition to the door of the ice making compartment) and thus the surface of water or ice within the ice tray may easily become in a wavy state.
Further, in order to accurately control a water-supply quantity to an ice tray and to accurately discriminate existence of water and ice within the ice tray, an ice making device which is currently used is provided with a plurality of sensors or a complicated control program and thus its cost is increased.
Further, in the structure of the ice making device described in US 2006/0201170, in which a water-supply quantity to an ice tray is controlled by an electrostatic capacity sensor, the electrode structuring the electrostatic capacity sensor is exposed on an inner side of the ice tray and thus the electrode may be corroded by water within the ice tray and, as a result, the water-supply quantity cannot be controlled accurately. Further, the water may be polluted by corrosion of the electrode to occur a hygienic problem.